Ell cycle regulation. Pon-A Exposure of SYK-deficient U373 cells stably transfected with wildtype SYK gene induces expression of SYK and activates downstream signaling events mimicking oxidative stress-induced activation of SYK and SYK-dependent signal transduction pathways (Uckun et al., 2010a). In order to acquire insights into the function of SYK as a centrosomal protein, we first examined the impact of SYK expression levels around the expression levels of cell cycle regulatory genes in human cells working with this ecdysoneinducible mammalian expression method (Uckun et al., 2010a). The eukaryotic cell division cycle has been shown to rely on an intricate sequence of transcriptional events associated with distinct cell cycle regulated gene expression patterns (Rowicka et al., 2007). Gene set enrichment evaluation (GSEA) showed that SYK induction in U373 cells causes a significant down-regulation of evolutionarily conserved genes associated with mitosis (Fig. 2a, normalized enrichment score: -2.48, false discovery rate b 0.0001, P b 0.0001) and cell cycle progression (Fig. 2b, normalized enrichment score: -2.44, false discovery price b 0.0001, P b 0.0001).The down-regulated genes in SYK-induced U373 cells included the human homologs of five yeast genes (viz.: CDC20, TAL1, PGM2, DBF4, BUB3) (Fig. 2c ) previously demonstrated to have peak expression inside the G2 and M phases from the yeast cell cycle. Information for the cell cycle distinct expression of these yeast genes was determined by high-resolution timing of cell cycle-regulated gene expression determined by genome-wide gene expression data of synchronized yeast cultures (Rowicka et al., 2007). Amongst the 53 down-regulated genes, the most substantially affected 10 genes exhibiting the greatest fold-difference values were PTTG1 (10.4-fold reduce, P = 0.0097), UBEC2C (eight.5-fold decrease, P = 0.0033), CDC20 (eight.4-fold reduce, P = 0.002), AURKA (eight.3-fold lower, P = 0.0059), CDC25C (7.8-fold decrease ,GSE18798 P = 0.0076), CCNB1 (7.4-fold reduce, P = 0.0045), CCNB2 (six.8-fold reduce, P = 0.0029), BUB1B (six.4-fold decrease , P = 0.007), BUB1 (5.6-fold reduce, P =0.0047), and SPAG5 (five.4-fold decrease, P = 0.0178) (accession #: GSE18798) (Fig. S1). Moreover, 15 genes for essential regulatory proteins with anti-proliferative functions which include DUSP1 (three.7-fold improve, P = 0.0005), SEPT4 (1.9-fold boost, P =0.018), SEPT7 (1.7-fold boost, P = 0.019), and GAS1 (two.4-fold enhance, P = 0.034) showed a moderate increase in expression following SYK induction (Fig. S1). The serine/threonine kinase ATM, encoded by the Ataxia telangiectasia-mutated (ATM) gene, is activated by DNA damage (viz.: double-stranded DNA breaks) and is expected for G2 checkpoint activation, which is responsible for inhibition of G2/M Ang2 Inhibitors products transition following DNA damage (Innes et al., 2006; Stracker et al., 2008). Within this context, ATM signaling delays the entry into mitosis by causing inactivation of CDC25C and thereby enforces the G2 checkpoint. ATM-dependent G2 checkpoint activation in irradiated mouse cells is connected with down-regulation of a special group of hugely correlated genes. Notably, the human homologs of numerous ATM-responsive G2 checkpoint signature genes were also down-regulated by induction of SYK expression in human U373 cells (Fig. 2f g). A cluster of two genes (AURKA and CCNB1) showed greater than 5-fold reduce, a cluster of three genes (CKS2, GAP43, NCAPD2) showed greater than 3.5-fold lower and also a cluster of 3 genes (HMGB2, FOXM1, N.
